Draft control



B. C. BERTRAM DRAFT CONTROL Nov. 19, 1940.

4 Sheets-Sheet 1 Bar/ [3 B e f/11m By 453' Filed Nov. 2, 1938 Nov. 19,1940.

B. c. BERTRAM 2 ,222,501

DRAFT CONTROL Filed Nov. 2, 1938 4 Sheet-Sheet 2 Nov. 19, 1940. B. c.BERTRAM 2,222,501

DRAFT CONTROL Filed Nov. 2, 1938 4 Sheets-Sheet 3 jizwfl far Barf (IBer/ram ,[zfor/tey;

Nov. 19, 1940. B. c. BERTRAM DRAFT CONTROL Filed Nov. 2, 1938 4Sheets-Sheet 4 wfiw v z e V hm a B/ y B w f Q g 6 m8 Patented Nov. 19,1940 UNITE-D STATES PATENT OFFICE 22 Claims.

This invention relates to draft appliance controls and more particularlyto controls for steam locomotive draft appliances and the like.

' An object of the present invention is to automatically control andstabilize the back pressure of the exhaust steam that is effective inthe draft appliance of a steam locomotive or the like to induce thedraft for the fire.

An additional object is to automatically adjust the back pressure of theexhaust steam in a steam locomotive and thereby regulate draft causedthereby so as to so control the volume of air drawn through the fire asto assure proper combustion of the fuel in the fire box of thelocomotive at all times during the operation of the latter.

It is to be noted, in this connection, that back pressure in alocomotive is the pressure effective on the pistons of the locomotiveand which is impressed thereon by the exhaust or spent steam from thecylinders and that such exhaust steam is customarily discharged throughthe smoke chamber and smoke stack of the locomotive so as to create aninduced or artificial draft of air through the fire box, flues andcombustion chamber and thus effect combustion of the fuel in the firebox as well' as of the fuel gases in the fire box, flues and combustionchamber.

It has been found, however, that the proper regulation of the backpressure in a locomotive and the resulting draft caused thereby, and theadjustment or accommodation of the back pressure and draft to theoperating needs of the locomotive are, in actual practice, accompaniedby a number of difficulties. Thus, for example, if the back pressure istoo high it causes excessive draft and in so doing effects a waste offuel in two ways, namely, first, by exerting an undesirable opposingforce to the action of the useful work performed by the live steam inoperating the pistons in the cylinders, as well as the other workingparts of the locomotive, and, second, by inducing too much draft throughthe fire box and flues of the locomotive, thus causing tearing of thefire, loss of fuel, cinder cutting, and other damage to thelocomotiveresulting from excessive draft, especially such as may arise fromdrawing unconsumed particles of fuel through the combustion chamber,smoke chamber and stack, and the like.

On the other hand, if the back pressure of the exhaust steam is too low,and the consequent air draft through the fire box is too low to assureproper combustion of the fuel in the fire box of the locomotive, theresult is likewise a waste of fuel which is frequently indicated by thedischarge of heavy black smoke, representing unconsumed carbon, from thesmoke stack of the locomotive, and also such reduced quantity of airresults in the production of carbon monoxide rather than carbon dioxidewith a pronounced loss in heat value.

It will be seen, therefore, that it is distinctly important in alocomotive, to assure both efficiency and economy in fuel consumption,that the back pressure of. the exhaust steam, and the draft inducedthereby, be maintained at a minimum but yet high enough to furnishsufficient oxygen to assure complete combustion of the fuel in the firebox, and it is another object of the present invention to provide a newand improved device for accomplishing this result.

It should be noted, in this connection, that attempts have heretoforebeen made to employ both manually operated and automatically operatingback pressure and draft appliance control devices in locomotives.However, none of such earlier manually operated devices, in so far as Iam aware, has ever been successful because, among other reasons,manually operable back pressure and draft control devices areimpractical in that such devices do not automatically, and thereforereadily, respond to changes in back pressure of the exhaust steam. 1

Likewise, none of the earlier automatic back pressure and-draft controldevices has, in so far as I am aware, been successful because, amongother reasons, such automatic devices have employed a singlespring-urged control valve for automatically controlling the fiow of theexhaust steam from the cylinders to and through the exhaust passages tothe smoke stack.

I have found, however, that single springurged valves cannot be used'forcontrolling the back pressure of the exhaust steam in its passage fromthe cylinders to and through the smoke stack, because, among otherreasons, such valves are responsive to and pulsate with the exhaustcycles of the locomotive, that is, unseat and close four times in eachrevolution of the driver wheels and, in so doing, wear themselves out ina comparatively very short length of time.

Hence, other objects of this invention are to overcome the foregoing andkindred difficulties which have been experienced in prior back pressureand draft appliance control devices; to associate pressure responsivemeans with controls of the aforesaid character that are operative toadjust the induced draft to the air requirements in the fire box of thelocomotive so as to'assure proper fuel combustion both during ordinaryoperating conditions and extraordinary operating conditions as, forexample, such as arise when the driver wheels of the locomotive slip onthe rails which usually induces such excessive draft that tearing of thefire, cinder cutting, loss of fuel and the like take place; to preventresponse of a pressure-operated locomotive'draft appliance control tonormal variations or pulsation's in back pressure; to utilize a multiplevalve responsive to the back pressure which will neverthelessautomatically function to stabilize the back pressure and the draftinduced thereby and thereby sudden and violent increases or decreases inthe back pressure are prevented; to insure the flow of suflicient oxygenthrough the fire box of a locomotive toeifect complete combustion duringall operating conditions and thereby reduce the amount of smoke producedso that the view of the engine and train crews of the track and signalswill not be impaired whereby safety of train operation will be promoted;to employ a mechanically-operated valve and means associated therewithto stabilize the operation of a locomotive draft appliance; to prevent amechanically-operated valve as aforesaid from effecting sharp or violentvariations of the locomotive draft appliance; to enable a relativelyhigh percentage of the grate area in a locomotive fire box to be devotedto air openings so as to facilitate the supply of air to the fire andinsure proper combustion but at the same time to avoid the supplying ofexcessive air to the fire and thereby prevent tearing of the fire andkindred detrimental effects; and to enable a locomotive draft appliancecontrol to be regulated under control of the steam supply to thestoker-operating engine of a locomotive whereby the operation of thecontrol will be automatically adjusted to the quantity of fuel beingsupplied to the fi e box.

Other objects and advantages will be apparent from the followingdescription in which reference is made to the accompanying drawingswherein Fig. 1 is a fragmentary side elevational view of a modernlocomotive showing a preferred form of the present invention appliedthereto, and wherein a part of the wall of the smoke chamber is brokenaway so as better to illustrate the association of the present inventiontherewith;

Fig, 2 is a transverse vertical sectional view on line 2-2 in Fig. 1,through the smoke chamber of the locomotive, and showing the parts ofthe present invention which are associated therewith;

Fig. 3 is an enlarged sectional view, on line 33 in Fig. 2, illustratingatypical and preferred form of automatic back pressure stabilizing andcontrol valve which may be used in connection with and as a part of thepresent invention;

Fig. 4 is an enlarged sectional view on line 44 in Fig. 1, illustratinga typical and preferred form of valve which may be used for the purposeof controlling the passage of steam from the steam supply line of thestoker-operating engine to the cylinder of the main control valve whichis shown in Fig. 3;

Fig. 5 is a transverse sectional view similar to Fig. 2, through thesmoke chamber of a locomotive but illustrating a modified form of thepresent invention associated therewith;

Fig. 6 is a fragmentary side elevation view illustrating the front endportion of a locomotive and showing the modification of the inventionwhich is shown in Fig. 5 associated therewith;

Fig. 7 is a sectional detail view illustrating a typical form ofmechanically operated control valve which may be used in, and isembodied in, the modified form of the invention which is illustrated inFigs. 5 and 6;

Fig. 8 is an end elevational View of a typical form of mechanicallyoperated control valve which is illustrated in Fig. 7; and

Fig. 9 is a central vertical sectional view illustrating a typical formof the back pressure stabilizing device which is embodied in the form ofthe invention which is illustrated in Figs. 5, 6, 7 and '8.

A preferred and typical form of the present invention is illustrated inFigs. 1 to 4, inclusive, and is therein illustrated in conjunction witha modern type of locomotive which is illustrated, in part, in Fig. 1 andis therein generally indicated by Hi, only such parts of the locomotivebeing illustrated, and being referred to hereinafter, as are necessaryfor the purpose of explaining the construction and operation of thepresent invention.

The locomotive l0 includes the usual smoke chamber H, smoke stack I2,exhaust stand [4 in the smoke chamber below and aligned with the stackI2, such parts comprising, in the main, the draft appliance of thelocomotive which also includes cylinders l3, grates l5, andstoker-operating engine which is generally indicated at l6; thestoker-operating engine being of the steamoperated type and steam foroperating the same being supplied thereto bymeans of a supply line orpipe IT.

A by-pass It! leads from the exhaust stand 14 to the inlet of a valve,generally indicated by 19, which includes an outlet 60 from which anexhaust pipe 90 leads to the atmosphere. The valve l9 controls dischargeof exhaust steam flowing from the exhaust stand [4 through the by-passI6 to the atmosphere through the exhaust pipe 90.

The valve l9 includes a valve casing 24 in which there is a plate 28that is disposed intermediate the inlet 25 and the outlet 60. The plate28 has a plurality or row of openings therein into which the lower endsof the valve seats 29 are screw-threaded in such a way that the valveseats 29 project beyond the plate 28 on the side thereof disposed awayfrom the inlet 25. As best shown in Fig. 3, the valve seats 29 havedomes that are disposed in spaced relation with the plate 28 and thedomes 30 are of such nature that the portions of the valve seats 29 thatproject beyond the plate 28 are substantially bell-shaped. Similarlyshaped valves 26 are provided which are disposed over the dome portions30 of the valve seats 29 and which have parts that extend down overtheportions of the sides of the valve seats 29 that project beyond theplate 28 to close the ports 3| provided in the valve seats 29. There isvery slight clearance, as at C, between the sides of the valve seats 29and the sides of the valves 30, and chambers D are defined between thedome portions 30 of the valve seats and the complementary parts of thevalves. In practice steam from the inlet 25 may leak through theclearances as C into the aforesaid chambers D to cause the valves 26 tobe elevated and thereby disclose the ports 3|.

Stems 29 have corresponding ends thereof s'ecured in the upwardlydisposed portions of the valves 26 and these stems extend throughopenings in a backing plate 36. Spring seats 30 are provided in thevalves 26 about the stems 29',

and other spring seats 3| are provided on the backing plate 36 about thestems 29, and springs 34 are disposed about the stems 29' and haveopposite ends thereof arranged in the spring seats 39' and 3|.

A bar 39 is disposed between the backing plate 36 and the cover plate 5|that is secured to the valve casing and at spaced intervals along thisbar pairs of rollers 38 are provided, one roller of each pair riding onthe underside of the cover plate 5| and the other roller of each pairengaging the backing plate 36.

Steam admitted into the valve casing 24 on one side of the plate 28 andleaking through a clearance'C and into the chambers D must overcome theeffective pressure of the springs 34 prior to the time the valves 26 canbe moved to disclose the ports 3|, the pairs of rollers 38 on the bar 39backing up the plate 36 which, in turn, backs up the springs 34. Whenthe pressure of the steam entering the valve casing 24 through the inlet25 is of a predetermined amount, the valves 26 disclose the ports 3| topermit the steam to flow through these ports from the inlet 25 to theoutlet 66.

In addition to the valve seats 29 and valves 26, auxiliary valve seats33, corresponding to the valve seats 29, are provided and valves 21cooperate with the valve seats 33, the valves 21 being seated over thedome portions 35 of the valve seats 33 which correspond to the domeportions 30 of the valve seats 29. Stems 50, corresponding to the stems29', have corresponding ends thereof fast in the upper portions of thevalves 21, and these stems extend through springs 48 which havecorresponding ends thereof disposed in valve seats 48' on the valves 21,the opposite ends of the springs being arranged in spring seats 52provided on the underside of discs 49. The discs 49 are supported fromthe cover plate 5| and the stems 50 extend therethrough.

The auxiliary valve seats 33 and the valves 21 are provided to take careof surges in pressure of the steam admitted through the inlet 25 andalso to afford additional outlets in event the volume of steam flowingthrough the inlet 25 is greater than can be accommodated by the valves26. In view of this it is preferable to arrange the springs 48 to havegreater tension than the springs 34 so that higher pressure need beapplied in the chambers D betweenthe domes 35 and the valves 21 in orderto disclose the ports 28' in the valve seats 33. For example, if thesprings 34 are arrangedto resist pressures applied in the chambers D upto five pounds, then the springs 48 may be arranged to resist pressuresup to ten pounds in the chambers D although it will be understood thatthe ratio between the effective resistance of the springs 34 and 48 maybe other than two-to-one as dictated by the circumstances under whichthe valve I9 is used.

It has been customary heretofore to so arrange the grates in the firebox of a locomotive that approximately not more than twenty-two percentof the grate is devoted to air openings for it has been found that if agreater percentage of air openings is provided in the grates, then underthose conditions where a high draft is induced by steam emitted from theexhaust stand I4 the fire will be torn or otherwise detrimentallyaffected. It will be apparent, however, that if a larger percentage ofair openings is provided in the grates of a locomotive, more oxygen willbe admitted and this will be conducive to more efficient combustion ofthe fuel. While the desirability of this condition has heretofore beenappreciated, it has not been possible to attain this because it has beenfound that where, for example, the percentage of air openings in thegrates was as high as forty percent the fire would be torn or otherwisedetrimentally affected if the driving wheels of a locomotive should slipon the rails or if for other reason the quantity and pressure of thesteam emitted from the exhaust stand I4 was excessive.

However, in accordance with the practice of my invention I arrange thegrate of the locomotive in such a way that air openings up to as much asforty percent of the grate may be provided and my invention operates toprevent tearing of the fire and the like, and this is accomplished inthe following manner.

As stated heretofore, the springs 34 controlling the valves 26 in thecontrol valve I9 are arranged to open when predetermined steam pressureis built up in the chambers D, and this adjustment of the springs 34 issuch that under all normal operating conditions the valves 26 are opento disclose the ports 3| and permit steam to flow from the inlet 25 tothe outlet 69 in such a way that the volume and pressure of steamemitted from the exhaust stand I4 into the stack I2 will not induce sucha draft that the, fire will be torn or otherwise detrimentally affected.On the other hand, the springs 34 are so adjusted that they will socontrol operation of the valves 26 that sufficient draft will be inducedby steam emitted from the exhaust stand I4 to insure proper combustionof fuel on the grates I5.

By way of example, if the percentage of air openings in the grate I5 isforty percent, the springs 34 may be advantageously adjusted to resistpressures up to five pounds in the charmbers D, but when pressure in thechambers D exceeds this amount it starts to open the valves 26 todisclose the ports 3| and the degree of opening of the valves 26 will bein direct proportion to the pressure in the chambers D so that if thepressures rise to say eight pounds substantial area of the ports 3| willbe disclosed so as to permit rapid fiow of steam to the outlet 66.

It will be noted that the by-pass I8 leads from the exhaust stand I4 tothe inlet 25 of the valve I9 and that the exhaust pipe 99 is connectedto the outlet 69 of such valve I9. Preferably, though not necessarily,the exhaust pipe 90 discharges in front of the stack I2 of thelocomotive so that any steam escaping through the exhaust pipe 90 willbe caught in the blast being emitted from the stack I2 and carriedupwardly so as to prevent this steam being thrown toward the cab of thelocomotive. Thus whenever the volume of pressure of steam flowing fromthe exhaust stand I4 is greater than that which will insure propercombustion of the fuel on the grate I5, the valves 26 open to disclosethe ports 3| and thereupon steam is by-passed from the exhaust stand I4to escape through the exhaust pipe 90, and in this way the volume ofsteam emitted from the exhaust stand I4 to the stack I2 to induce thedraft is so controlled that damage to the fire on the grate I5 isavoided.

It is recognized that there will be excessive surges of steam toward theexhaust stand I4 and through the by-pass I8 as where the driving wheelsof the locomotive slip on the rail or where the locomotive is improperlyoperated in such a way as to supply excessive steam to the cylinthat theauxiliary valves 21 are provided for when there is an excessive surge inpressure or an excessive quantity of steam emitted through the inlet 25then the pressure will be such as to build up in the chambers D' in sucha way as to overcome the effective resistance of the springs 48 and inthis way the ports 28' will be disclosed. As many valves 21 andconsequently ports 28 will be provided as will be necessary to insurethat irrespective of the quantity of steam admitted through the inlet 25over and above that normally expected will be discharged through theexhaust pipe 90, and it will therefore be seen that the auxiliary valves21 afford reserve escapes for the steam and serve to care i for abnormalconditions.

In locomotive operation there will be occasions where it will bedesirable to increase the firing rate as where the steam pressure fallsbelow that required for the particular condition under which thelocomotive is operating and in such instances fuel over and above thatnormally supplied to the grates |5 is supplied thereto. In stoker firedlocomotives this is effected by increasing the effective pressure of thesteam admitted through the pipe I! to the stoker engine so as toincrease the operating speed of this engine and thereby supplyadditional fuel to the grates l5. In such instances and becauseadditional fuel is being supplied it is desirable that the draft beincreased which, of course, is to be effected by emitting additionalsteam from the exhaust stand M to the stack l2. With the apparatus asthus far described this would be prevented for the reason that both thevalves 26 and 21 would open in such an instance and instead ofadditional steam being discharged from the stand M to the stack |2 theadditional steam would be discharged through the exhaust pipe 90.

Thus in those instances where it is desirable that the induced draft beincreased an arrangement is provided for increasing the efiectiveresistance of the springs as 34, wherefore pressures in excess of thatnormally built up in the chambers D will be required in order to openthe valves 26 so as to disclose the ports 3|. To this end cams 31 areprovided on the backing plate 36 to lie in the path of the rollers 38that normally engage the backing plate 36 and when it is desirable thatthe effective pressure of the springs 34 be increased, as incircumstances such as those just described, the rollers 38 are caused toride up onto the cams 31 whereupon the backing plate 36 is forced towardthe valves 26 which obviously increases the compression or effectivetension of the springs 34.

It has been explained heretofore that the rollers 38 are mounted on abar 39. This bar 39 has an extension 40 projected outwardly of the valvecasing 24 and the extension 49 is pivotally connected, as indicated at46, to a rocker 45. The rocker 45 is pivotally connected, as indicatedat 44, to a link 45' that is pivotally mounted, as indicated at 46', ona lug 47' on the valve casing 24. A stem 43 is pivotally connected, asindicated at 44, to the rocker 45 and this stem is also connected to apiston 4| in the cylinder 23, the cylinder 23 also being mounted on thevalve casing 24. Whenever it is desired to increase the tension of thesprings 34, steam is admitted to the cylinder 23 whereupon the piston 4|is forced outwardly against the action of the spring 42, confined in thecylinder 23 and effective on the piston 4|, whereupon, through the stem43,

the rocker 45 is moved so that the bar 39 is moved to thereby move therollers 38 up onto the cams 31.

It has been explained that it is desirable to increase the tension ofthe springs 34 in the manner just described whenever it is desired tocombust a quantity of fuel over and above that normally consumed on thegrate l5. It will, of course, be understood that manually operated meansmay be provided for supplying steam to the cylinder 23 to operate thepiston 4| in the manner just described and in manually fired locomotivessuch an arrangement would be provided. However, it is desirable that theoperation of my novel apparatus be rendered automatic as far as possibleand hence in those locomotives equipped with a stoker-operating engineI6, to which a steam line I is led to supply steam thereto to effectoperation thereof, a steam line is led from the steam line II to theinlet 54 of a pressure-responsive valve generally indicated by 2|. Asteam line 22 leads from the outlet 55 of the valve 2| to the cylinder23.

The valve 2|, which is shown in detail in Fig. 4,

' valve 59 and has a diaphragm piston 56 associated therewith, a spring58 being efiective on the diaphragm piston 56 to normally hold theneedle valve 59 in position to close the orifice 59'. The spring 58 isenclosed in a housing 53 in which a spring adjusting nut 53' is providedso that the eiTective tension of the spring 58 may be varied.

It will be understood that the steam line 20 is connected to the steamline H intermediate the control valve for the steam line I! and thestoker engine I6. It will also be understood that the speed of operationof the stoker engine i6 and therefore the quantity of fuel supplied tothe grate I5 is dependent upon the pressure of the steam admittedthrough the pipe I! to the engine |6. In view of this the spring 58 isso adjusted that so long as the effective pressure in the steam line I!is not in excess of what will be called normal pressure, which is tosay, pressure suflicient to so operate the engine l6 that a sufiicientquantity of fuel will be supplied to the grate l5 to care for normaloperating conditions of the engine, then the needle valve 59 remainsseated to close off flow through the orifice 59'.

When, however, the steam pressure in the steam line I! is increasedabove the aforesaid normal then such pressure is efiective through thesteam line 20 and inlet 54 on the diaphragm 51 whereupon the needlevalve 59 is retracted from closing position with respect to the orifice59' and hence steam will flow from the inlet 54 to the outlet 55 andthence to the cylinder 23 to effect operation of the piston 4| in themanner above described.

It will be manifest that pressure in the steam line I! will be reducedprior to the time all of the additional fuel supplied to the grate l5has been consumed and for this reason it is desirable that the rollers38 remain in engagement with the cams 31 for a short time after pressurein the steam line I! is reduced. This is accomplished by providing forthe entrapment of steam effective on the diaphragm 51 and providing anescaping port 51' in the outlet passage 55. Thus when steam has onceunseated the needle valve 59, this needle valve remains unseated fromthe port 59' as steam slowly escapes from the port 51' and until thepressure exerted on the diaphragm 51 is in such a degree'that the spring58 will overcome this pressure and reseats the needle valve 59. Anadjustment afforded by the screw plug 58' for the exhaust port 51'enables this escape of steam to be so adjusted that the effective steampressure in the cylinder 23 is not reduced, so as to enable the sprig 42to dispose the bar 39 in the position in which it is shown in Fig. 3,until the excess quantity of fuel admitted to the grates in the mannerabove described has been consumed so that in this way an automaticarrangement is provided for insuring proper combustion of the fuel evenunder those circumstances where an abnormal quantity of fuel is suppliedto the grates l5.

In the use of my novel apparatus as thus far described the percentage ofair openings in the grate is ascertained and the springs 34 are adjustedto hold the valves 26 closed so long as the pressure and volume of steamsupplied to the exhaust stand l4 does not induce a draft in excess ofthat required for proper combustion of the fuel. When, however, steampressure in the exhaust stand I4 and therefore in the by-pass l8 exceedsthat which would induce a proper draft, it being understood that thedegree of induced draft is in direct proportion to the pressure of steamemitted from the exhaust stand l4 toward the stack l2, then, first ofall, the valves 26 open by reason of an increase in pressure in thechambers D as steam leaks through the clearances C thereinto. Undernormal operating conditions onl the valves 26 will be opened in thosecircumstances where the pressure of steam being emitted from the exhauststand I4 is greater than that required to induce a proper draft, andsuch opening of the valves 26 causes the excess steam to flow throughthe by-pass l8, valve l9 and exhaust pipe 96 to be discharged to theatmosphere.

What I have referred to hereinabove as the auxiliary valves 21 are, inreality, protection valves and these valves only function in thoseinstances where abnormal conditions arise such as are induced byslippage of the driver wheels of the locomotive, and in such an instancethere will be an abnormal rise in the back pressure of the steam andthis will overcome the tension of the springs 48 and open the protectionvalves 2'! whereupon additional outlets for the steam are afforded sothat abnormal surges of steam are taken care of and abnormal increasesin back pressure which might cause an abnormal increase in draft areavoided.

The valves 26 are opened, as explained, by building up pressure in thechambers D, and such valves once opened remain open. until the steamaccumulated in the chambers D escapes therefrom through the relativelysmall clearances C, and this is also true of the protection valves as 21which are opened by building up pressure in the chambers D. It will berecognized that in normal locomotive operation the back pressurepulsates by reason of the intermittent discharge of steam from thecylinders in each revolution of a river wheel and therefore the backpressure rises and falls. The rapidity of such pulsations is, of course,directly proportionate to the speed of operation of the driver wheels ofthe locomotive, and preferably the clearances C are such that under nocircumstance can steam so escape from the chambers D, intermediatepulsations induced in the back pressure by reason of steam escape fromthe cylinders, that even when the driver wheels of a locomotive areturning over quite slowly, the valves 26 once opened remain open untilthe mean of the back pressure falls below that which the springs 34 areset to overcome.

This arrangement is quite important for it eliminates pounding of thevalves such as might result if the valves were directly responsive tosteam pressure for such valves would of necessity open and close withthe pulsations of the steam escaping from the cylinders,.and suchoperation of the valves would so shorten the lives thereof as to renderthe device impractical. However, the steam collected in the chambers Dof the valves of my invention has a cushioning effect which preventssuch pounding of the valves.

It will be understood that other forms of cushion valves than thosewhich I have described might be used and furthermore means other thansteam-operated means might be used for causing the valves to open at ahigher pressure in a manner that is effected by operation of the bar 39as described above. Furthermore, it is within the purview of myinvention to employ a mechanically operated valve in place of thecushion valves, such as I have described above, but in order to preventsuch a mechanically-operated valve opening and closing in response topulsations in the back pressure caused by the intermittent escape of thesteam from the cylinders, it is necessary to employ, in those instanceswhere the mechanically-operated valve is employed, some means which willprevent the direct application of the back pressure on the means foroperating the mechanical valves.

An arrangement employing a mechanicallyoperated valve of a kind suitablefor use in the practice of my invention is illustrated in Figs. 5 to 9,inclusive, and by referring theretoit will be seen that a by-pass 6|leads through the smoke chamber 63 of a locomotive from the exhauststand 62 to the inlet 69 of a valve 65, which includes an outlet ID fromwhich an exhaust pipe 91 leads to the atmosphere in front of the stack64 just as the exhaust pipe 96 leads to the atmosphere in front of thestack I2 in the form of my invention shown in Figs. 1 to 4.

The valve 65 includes a substantially cylindrical valve casing 68 inwhich a sleeve II is provided. A chamber 69 is provided in the valvecasing 68 about the sleeve H and the inlet 69 leads to this chamber 69.A plurality of ports 12 is provided in the sleeve H and these portscommunicate with the chamber 69'.

A valve sleeve 13 is mounted in the sleeve H and has a plurality ofports 14 therein which, upon rotation of the valve sleeve 13, may bemoved into and out of alignment with the ports 12. When the ports 14 arealigned with the ports 12, communication is established between thechamber 69' and the interior of the valve sleeve 13 that leads to theoutlet of the Valve 65.

In the present instance a gear 15 is fast to the valve sleeve 13 at theend thereof opposite the end communicating with the outlet 10, and apinion 16 fast on the shaft 11 meshes with the gear 15, the shaft 11being mounted in the 010- sure plate 15' fast to the valve casing 68.The shaft 1'! extends beyond the closure plate 15 and has an arm 18 fastthereto.

A cylinder 82 is provided in which a piston BI is reciprocal against theeffect ofa spring 82'. A stem 88 leads from the cylinder 82 and has oneend thereof connected to the piston 8| and the opposite end of the stem88 is pivotally connected, as indicated at 19, to the free end of thearm 18.

A pipe 83 leads from the by-pass 6| to the intake of a pressurestabilizer 66 that includes a casing 84 having a pad 85- in the intakepassage thereof in which a stud 88 is fast to secure a plate 85 inposition to close the intake passage. The plate 85 has a plurality ofpassages 86 therein and a yieldable plate 81 normally lies over theupper ends of these passages to close the same, a fiat spring 88 actingon-the yieldableplate 81 to hold it in such passage closing position. A

chamber 84' is provided in the casing 84 above the plate 85 and a pipe61 leads from thechamber 84' to the cylinder 82 to admit steam from thechamber 84' into the cylinder 82 between the piston 8| and the head ofsuch cylinder.

1 In this form of my invention as in the previous form the-exhaust stand62 is arranged in the smoke chamber 63 below the stack 64 and is sizedto permit the emission therefrom of steam toward the stack 64 in such away as to induce the proper degree of draft under normal operatingconditions to effect efiicient combustion of the fuel on a grate as|5,'the degree of induced draft being proportionate tothe percentageofair openings in the grate so as to prevent tearing of the fire and otherdetrimental effects.

So long as the quantity of steam passing to the exhaust stand 62 is notgreater than that which will induce the proper degree of draft, thevalve sleeve 13 is so disposed that the ports 14 therein are out ofalignment with the ports 12 in the sleeve 1|. When, however, the steampressure exceeds a predetermined degree, such steam pressure beingreferred to herein as the back pressure inasmuch as it is the pressurewhich resists the effective work on the pistons of the locomotive, it iseffective through the passages 86 to unseat the plate 81 whereupon steam5 is admitted into the chamber 84' and so long as the chamber 84', pipe61 and cylinder 82 are in communication with the pipe 83, the pressurein the cylinder 82 and chamber 84 is equal to the pressure in the pipe83 and the by-pass 6|.

50 However, as has been explained heretofore, the

back pressure pulsates due to the intermittent 3 exhaustof steam fromthe cylinders and thus each time the pressure in the pipe 83 falls belowthe pressure of steam entrapped in chamber 84',

155 the spring 88 is effective on the plate 81 to seat this plate toclose off the passages 86, and this operates to maintain substantiallyconstant pressure in the cylinder 82.

However, when there is a drop in pressure in a 5 sages 86 therein, anadjusting screw 81' being provided to afford adjustment in the degree ofleakage from the chamber 84' past the plate 85. Steam leaking from thechamber 84'" through the vent or by-pass 86' causes a reduc- .70 tion inpressure in the chamber 84 with a consequent reduction in pressure inthe cylinder 82.

Whenever the pressure of the steam in the cylinder 821s sufficient toovercome the effect of the spring 82, the piston 8| is moved and 175this movement is transmitted through the stem 88 and arm 18 to the shaftI1 whereupon the pinion 16 is rotated which, of course, rotates the gear15 and the sleeve 13. Such rotation of the valve sleeve 13 brings theports 14 therein into registration with the ports 12 in the sleeve H andthe degree of registration of the ports 14 with the ports 12 controlsthe degree of steam flow from the by-pass 6| to the exhaust pipe 9|, thegreater the registration the greater the steam flow. Thus in directproportion to the degree of back pressure, the ports 14 and I2 arebrought into alignment to afford an escape to the atmosphere from theexhaust stand 62 through by-pass 6|, valve 65 and exhaust pipe 9| to theatmosphere, and in this way steam which might act to induce excessivedraft is discharged to the atmosphere.

Inasmuch as the steam which actuates the piston 8| and consequently theregistration of the ports 14 with the ports 12 is admitted into thecylinder 82 from the chamber 84' and since the steam pressure in thechamber 84' is stabilized, it is manifest that the piston 8| does notmove in response to pulsations in the back pressure such as are inducedby the intermittent exhaust-of steam from the cylinders. However,substantial changes in steam pressure in the exhaust stand 62 isefiective either through the passages 86 or the by-pass 86' to effectvariation of the steam pressure in the chamber 84' and consequently inthe' cylinder 82 wherefore movement of the piston 8| and the consequentregistration or de-registration of the ports 14 and I2 is effected indirect proportion to substantial variations in pressure in the exhauststand 62.

The ultimate effect of both of the above described forms of my inventionand equivalents thereof is to tend to stabilize the backpressure in sucha way as to control the volume and pressure of the steam emitted fromthe exhaust stands as I4 and 62, and in this way the degree of draftinduced in the firebox of a locomotive is maintained relativelyconstant.

In the form of my invention shown in Figs. 1 to 4 abnormal surges in theback pressure are compensatedfor by protection valves such as the valves21, and in the form of my invention shown in Figs. 5 to 9 such abnormalsurges are compensated for by substantially complete registration of theports '14 and 12, it being understood that these ports are so sized thatwhen they are in complete registration sufficient escape is afforded forsteam to care for the most excessive conditions that would beencountered in operation of the locomotive with which the device isassociated.

It will be manifest from the foregoing description that my inventioncontemplates stabilizing the back pressure in a locomotive in such a wayas to enable substantially the maximum percentage of air openings to beafforded in a grate for, by reason of the control of the induced draftthat is afforded by my invention, the likelihood of tearing the fire andother detrimental eifects of the excessive'induced draft are overcome.Thus instead of substantially reducing the percentage of air openings ina grate to produce what is referred to as choked effect, it is possibleto afford the percentage of air openings in the grate which will beconducive to the most efficient combustion of the fuel passed to thegrate. It will be manifest that such eflicient combustion of the fuelwill enable the attainment of marked fuel economies.

A further important advantage of my invention is that not only isefilcient combustion of the fuel effected but I make it possible'to moreefficiently utilize the work produced, which is to say, by reason ofstabilization of the back pressure and preventing the back pressure frombecoming excessive I make it unnecessary to overcome that degree of backpressure which would detrimentally interfere with efficient operation ofthe locomotive, for it will be apparent that the greater the backpressure the more resistance there is to the effective work being donein the cylinders of the locomotive and by stabilizing the back pressureand preventing it from building up excessively I make it unnecessary toovercome objectionable back pressure.

A very important aspect of my invention is that the means are providedfor stabilizing the back pressure, such means being the restrictedclearances C in the form of my invention shown in Figs. 1 to 4 and theparts providing the chamber 84' in the form. of my invention shown inFigs. 5 to 9. These means, which operate in response to variations or,better, increases in back pressure, are such that they are notresponsive to the pulsations or intermittent increases and decreases inback pressure such as are induced by the intermittent exhaust from thecylinders of a locomotive. It is very important that any such pressureresponsive means employed in the apparatus be such that it will not beresponsive to such pulsations in back pressure for otherwise theapparatus will continually open and close which will result in poundingof reciprocatory parts and rapid wear of the parts which move relativeto one another, either of which conditions is obviously objectionable,for either and kindred conditions will so shorten the life of theapparatus that the other economies realized by use of a device such asthat to which my invention pertains are overcome because of the frequentreplacement necessitated where parts wear out rapidly.

Other and further advantages of my invention will be apparent to oneskilled in the art and while I have illustrated and described selectedembodiments of my invention, it is to be understood that these arecapable and susceptible of variation and modification and I therefore donot wish to be limited to the precise details set forth but desire toavail myself of such changes and alterations as fall within the purviewof the following claims.

I claim:

1. The improvement in locomotive draft appliance controls, where theappliance includes a steam exhaust passage terminating in a dischargenozzle, which consists in means providing an outlet to the atmospherefrom said exhaust passage in advance of said discharge nozzle, valvemeans responsive to steam pressure in said exhaust passage forregulating the discharge of steam from said passage through said outletand which valve means is constructed and arranged to open when a steampressure above a predetermined steam pressure is established in saidpassage, and means operable to delay the closing of said valve meansupon decrease in the pressure in said passage and functioning to causethe valve means to remain open after decrease in the pressure below saidpredetermined pressure for a period of time proportionate to the degreeof pressure above said predetermined pressure that has been eifective toopen said valve means.

2. The improvement in locomotive draft appliance controls, where theappliance includes a steam exhaust passage terminating in a dischargenozzle, which consists in means providing an outlet to the atmospherefrom said exhaust passage in advance of said discharge nozzle, valvemeans in said outlet and responsive to steam pressure in said exhaustpassage for regulating the discharge of steam from said passage throughsaid outlet and which valve means is constructed and arranged to openwhen a steam pressure above a predetermined steam pressure isestablished in said passage, and means included in said valve means andoperable to delay the closing of said valve means upon decrease in thepressure in said passage and functioning to cause the valve means toremain open after decrease in the pressure below said predeterminedpressure for a period of time proportionate to the degree of pressureabove said predetermined pressure that has been effective to open saidvalve means.

3. The improvement in locomotive draft appliance controls, where theappliance includes a steam exhaust passage terminating in a dischargenozzle, which consists in means providing an outlet to the atmospherefrom said exhaust passage in advance of said discharge nozzle, valvemeans in said outlet for regulating discharge of steam from said passagethrough said outlet, means responsive to steam pressure in said exhaustpassage for operating said valve means and which pressure responsivemeans is constructed and arranged to open said valve means when a steampressure above a predetermined steam pressure is established in saidpassage, and means interposed between the pressure responsive means andsaid exhaust passage and operable to delay the closing of said valvemeans upon decrease in the pressure in said passage and functioning tocause the valve means to remain open after decrease in the pressurebelow said predetermined pressure for a period of time proportionate tothe degree of pressure above said predetermined pressure that has beeneffective to open said valve means.

4. The improvement in locomotive draft appliance controls, where theappliance includes a steam exhaust passage terminating in a dischargenozzle, which consists in means providing an outlet to the atmospherefrom said exhaust passage in advancce of said discharge nozzle, valvemeans responsive to steam pressure in said exhaust passage forregulating the discharge of steam from said passage through said outletand which valve means is constructed and arranged to open when a steampressure above a predetermined steam pressure is established in saidpassage and which valve means includes means wherein steam from saidpassage is entrapped upon the opening of said valve means, and means fordelaying the escape of entrapped steam to a predetermined rateindependently of and upon decrease in the pressure whereby said valvemeans remains open after decrease in the pressure below saidpredetermined pressure for a period of time proportionate to the degreeof pressure above said predetermined pressure that has been effective toopen said valve means.

5. The improvement in locomotive draft appliance controls, where theappliance includes a steam exhaust passage terminating in a dischargenozzle, which consists in means providpassage through said outlet andwhich valve means is constructed and arranged to open when a steampressure above a predetermined steam pressure is established in saidpassage and which valve means includes means wherein steam from saidpassage is entrapped, and means including a restricted passage providingfor the escape of entrapped steam at a predetermined rate independentlyof and upon decrease in the pressure whereby said valve means remainsopen after decrease in the pressure below said predetermined pressurefor a period of time proportionate to the degree of pressure above saidpredetermined pressure that has been effective to open said valve means.

6. The improvement in locomotive draft appliance controls, where theappliance includes a steam exhaust passage terminating in a dischargenozzle, which consists in means providing an outlet to the atmospherefrom said exhaust passage in advance of said discharge nozzle, valvemeans in said outlet for regulating discharge of steam from said passagethrough said outlet, means responsive to steam pressure in said exhaustpassage for operating said valve means and which pressure responsivemeans is constructed and arranged to open said valve means when a steampressure above a predetermined steam pressure is established in saidpassage, and means interposed between the pressure responsive means andsaid exhaust passage and wherein steam from said passage is entrappedand including means for delaying the escape of entrapped steam therefromto a predetermined rate independently of 40 and upon decrease in thepressure whereby said valve means remains open after decrease in 'thepressure below said predetermined pressure for a period of timeproportionate to the degree of pressure above said predeterminedpressure that 45 has been effective to open said valve means.

'7. The improvement in locomotive draft appliance controls, where theappliance includes a steam exhaust passage leading from the cylinders ofthe locomotive and terminating in a discharge 50 nozzle, which consistsin means providing an outlet to the atmosphere from said exhaust passagein advance of said discharge nozzle, valve means for regulating thedischarge of steam from said exhaust passage through said outlet andinclud- 55 ing a plurality of independent valve devices normally urgedinto position to close off steam flow from said exhaust passage to saidoutlet, each of said valve devices having operating means therefor, eachof said operating means being operative 50 to open the valve deviceassociated therewith and effect the discharge of steam from the exhaustpassage through said outlet in a degree proportionate to the steampressure in said exhaust passage, and each of said operating meansinclud- 65 ing means'operable to delay the closing of said valve meansand functioning to cause the valve means to remain open for a period oftime after decrease in the pressure below said predetermined pressure tothereby render the valve means unre- 70 spcnsive to such steam pressurevariations as are induced in the exhaust passage as an incident to theintermittent admission thereto of steam from the cylinders of thelocomotive.

8. The improvement in locomotive draft appli- 75 ance controls, wherethe appliance includes a steam exhaust passage leading from thecylinders of the locomotive and terminating in a discharge nozzle, whichconsists in means providing an outlet to the atmosphere from saidexhaust passage in advance of said discharge nozzle, valve meansresponsive to steam pressure in said exhaust passage for regulating thedischarge of steam from said passage through said outlet, said valvemeans including interengageable parts normally urged into engagement onewith the other to close off flow of steam from said exhaust passagethrough said outlet, and operating means for effecting separation ofsaid interengageable parts to permit flow of steam from the exhaustpassage through the outlet in a degree proportionate to the steampressure in said exhaust passage, said operating means including achamber into which steam from said exhaust passage may be admitted tobuild up pressure therein and thereby effect separation of saidinterengageable parts, and said operating means also including meansaffording a restricted passage between said exhaust passage and saidchamber and through which steam flows slowly from and to said exhaustpassage to and from said chamber whereby said operating means isrendered unresponsive to such steam pressure variations as are inducedin the exhaust passage as an incident to the intermittent admissionthereto of steam from the cylinders of the locomotive.

9. The improvement in locomotive draft appliance controls, where theappliance includes a steam exhaust passage leading from the cylinders ofthe locomotive and terminating in a discharge nozzle, which consists inmeans providing an outlet to the atmosphere from said exhaust passage inadvance of said discharge nozzle, valve means responsive to steampressure in said exhaust passage for regulating the discharge of steamfrom said passage through said outlet, said valve means including aplurality of independently interengag'eable parts normally urged intoengagement one with the other to close off flow of steam from saidexhaust passage through said outlet, and independent operating means foreach of said interengageable parts and operative to eifect separation ofthe interengageable parts associated therewith to permit flow of steamfrom the exhaust passage through the outlet in a degree proportionate tothe steam pressure in said exhaust passage, each of said operating meansincluding a chamber into which steam from said exhaust passage may beadmitted to build up pressure therein and thereby efiect separation ofthe interengageable parts associated therewith, and each of saidoperating means also including means afiording a restricted passagebetween said exhaust passage and said chamber and through which steamflows slowly from said exhaust passage to and from said chamber wherebysaid operating means is rendered unresponsive to such steam pressurevariations as are induced in the exhaust passage as an incident to theintermittent admission thereto of steam from the cylinders of thelocomotive.

10. The improvement in locomotive draft appliance controls, where theappliance includes a steam exhaust passage leading from the cylinders ofthe locomotive and terminating in a discharge nozzle, which consists inmeans providing an outlet to the atmosphere from said exhaust passage inadvance of said discharge nozzle, valve means for regulating thedischarge of steam from said exhaust passage through said outlet, steampressure operated means for said valve means in com- 'discharged fromthe .exhaust passage through said outlet in a degree proportionate tothe steam pressure in said exhaust passage and means interposed betweensaid operating means and said exhaust passage for regulating the supplyof steam to said operating means from said exhaust passage and operativeto render the operating means unresponsive to such steam. pressurevariationsas are induced in the exhaust passage as an incident to theintermittent admission thereto of steam from the cylinders of thelocomotive.

11. The improvement in locomotive draft appliance controls, where theappliance includes a steam exhaust passage leading from the cylinders ofthe locomotive and terminating in a discharge nozzle, which consists inmeans providing an outlet to the atmosphere from said exhaust passage inadvance of said discharge nozzle, valve means including interengageableparts normally urged into engagement one with the other to close offflow of steam from said exhaust passage through said outlet until apredetermined steam pressure is built up in said exhaust passage,operating means for effecting separation of said interengageable partsto permit flow of steam from said exhaust passage through said outlet ina degree proportionate to the steam pressure in said exhaust passage,said operating means including a chamber into which steam from saidexhaust passage may be admitted to build up pressure therein and therebyefiect separation of said interengageable parts, said operating meansalso including means affording a restricted passage between said exhaustpassage and said chamber and through which steam flows slowly from andto said exhaust passage to and from said chamber whereby said operatingmeans is rendered unresponsive to such steam pressure variations as saidinterengageable parts are urged into engagement with each other andoperative to prevent separation of said interengageable parts until apressure greater than the aforesaid predetermined pressure is built upin said exhaust passage.

12. The improvement in locomotive draft appliance controls, where theappliance includes a steam exhaust passage terminating in a dischargenozzle, which consists in means providing an outlet to the atmospherefrom said exhaust passage in advance of said discharge nozzle, valvemeans responsive to steam pressure in said exhaust passage forregulating the discharge of steam from said passage through said outletand which valve means is constructed and arranged to open whenpredetermined steam pressure is established in said passage and toremain open after decrease of such pressure below said predeterminedpressure for a period of time proportionate to the degree of pressureimpressed thereon above said predetermined pressure, and means operativeto prevent opening of said valve means until a steam pressure greaterthan the aforesaid predetermined steam pressure is established in saidexhaust passage.

13. The improvement in locomotive draft appliance controls, where theappliance includes a steam exhaust passage terminating in a dischargenozzle, which consists in means providing an outlet to the atmospherefrom said exhaust passage in advance of said discharge nozzle, valvemeans in said outlet and including means constructed and arranged toopen and permit dis- I charge of steam through said outlet whenpredetermined steam pressure is established in said passage and toremain open after decrease of such pressure below said predeterminedpressure for a period of time proportionate to the degree of pressureimpressed thereon above said predetermined pressure, and means operativeto prevent opening of said valve means until a steam pressure greaterthan the aforesaid predetermined steam pressure is established in saidexhaust passage.

14. The improvement in locomotive draft appliance controls, where theappliance includes a steam exhaust passage terminating in a dischargenozzle, which consists in means providing an outlet to the atmospherefrom said exhaust passage in advance of said discharge nozzle, valvemeans in said outlet for regulating discharge of steam from said passagethrough said outlet, means responsive to steam pressure in said exhaustpassage for operating said valve means and which pressure responsivemeans is constructed and arranged to open said valve means whenpredetermined steam pressure is established in said passage and tomaintain said valve means open after decrease of such pressure belowsaid predetermined pressure for a period of time proportionate to thedegree of pressure impressed thereon above said predetermined pressure,and means operative to prevent opening of said valve means until a steampressure greater than the aforesaid predetermined steam pressure isestablished in said exhaust passage.

15. .The improvement in locomotive draft appliance controls, where theappliance includes a steam exhaust passage leading from the cylinders ofthe locomotive and terminating in-a discharge nozzle, which consists inmeans providing an outlet to the atmosphere from said exhaust passage inadvance of said discharge nozzle, valve means including inte'rengageableparts normally urged into engagement one with the other to close ofiflow of steam from said exhaust passage through said outlet until apredetermined steam pressure is built up in said exhaust passage,operating means for effecting separation of said interengageable partsto permit flow of steam from said exhaust passage through said outlet ina degree proportionate to the steam pressure in said exhaust passage,said operating means including a chamber into which steam from saidexhaust passage may be admitted to build up pressure therein and therebyeffect separation of said interengageable parts, said operating meansalso including means affording lat-restricted passage between saidexhaust passage and said chamber and through which steamflows slowlyfrom and to said exhaust passage to and from said chamber whereby saidoperating means is rendered unresponsive to such steam pressurevariations as are induced in said exhaust passage as an incident to theintermittent admission thereto of steam from the cylinders of thelocomotive, means operative to increase the force by which saidinterengageable parts are urged into engagement with each other andoperative to prevent separation of said interengageable parts until apressure greater than the aforesaid predetermined pressure is built upin said exhaust passage, and auxiliary valve means openable to afiordcommuni cation betwen said exhaust passage and said outlet and operableto be opened upon a predetermined increase in pressure in the exhaustpassage above the aforesaid predetermined pressure.

16. The improvement in locomotive draft appliance controls, where theappliance includes a steam exhaust passage terminating in a dischargenozzle, which consists in means providing an outlet to the atmospherefrom said exhaust passage in advance of said discharge nozzle, valvemeans responsive to steam pressure in said exhaust passage forregulating the discharge of steam from said passage through said outletand which valve means is constructed and arranged to open whenpredetermined steam pressure is established in said passage and toremain open after decrease of such pressure below said predeterminedpressure for a period of time proportionate to the degree of pressureimpressed thereon above said predetermined pressure, and auxiliary valvemeans openable to afford communication between said exhaust passage andsaid outlet and operable to be opened upon a predetermined increase inpressure in the exhaust passage above the aforesaid predeterminedpressure.

17. The improvement in locomotive draft appliance controls, where theappliance includes a steam exhaust passage terminating in a dischargenozzle, which consists in means providing an outlet to the atmospherefrom said exhaust passage in advance of said discharge nozzle, valvemeans in said outlet and including means constructed and arranged toopen and permit discharge of steam through said outlet whenpredetermined steam pressure is established in said passage and toremain open after decrease of such pressure below said predeterminedpressure for a periodof time proportionate to the degree of pressureimpressed thereon above said predetermined pressure, and auxiliary valvemeans openable to afford communication between said exhaust passage andsaid outlet and operable to be opened upon a predetermined increase inpressure in the exhaust passage above the aforesaid predeterminedpressure.

18. The improvement in locomotive draft appliance controls, where theappliance includes a steam exhaust passage terminating in a dischargenozzle, which consists in means providing an outlet to the atmospherefrom said exhaust passage in advance of said discharge nozzle, valvemeans in said outlet for regulating discharge of steam from said passagethrough said outlet, means responsive to steam pressure in said exhaustpassage for operating said valve means and which pressure responsivemeans is constructed and arranged to open said valve means whenpredetermined steam pressure is established in said passage and tomaintain'said valve means open after decrease of such pressure belowsaid predetermined pressure for a period of time proportionate to thedegree of pressure impressed thereon above said predetermined pressure,and auxiliary valve means openable to afford communication between saidexhaust passage and said outlet and operable to be opened upon apredetermined increase in pressure in the exhaust passage above theaforesaid predetermined pressure.

19. In a device for use with a steam locomotive wherein steam exhaustedfrom means in the locomotive in which the steam is expanded to performwork builds up a back pressure and in which such steam is utilized toinduce a draft through the fire box of the locomotive of a magnitudeproportionate to the magnitude of the back pressure, outlet meansthrough which the exhausted steam may also be discharged to theatmosphere, valve means in said outlet means for controlling fiow ofsteam to the atmosphere through said outlet means, said valve meansincluding a plurality of pressure responsive valve members operable tobe opened upon increase of'the back pressure beyond a predeterminedmagnitude to permit discharge of sufiicient steam to the atmospherethrough said outlet means to prevent a substantial increase in the backpressure beyond said predetermined magnitude, each of said pressureresponsive valve members including a fixed member and a movable membershaped to define a chamber therebetween and sized to ailord restrictedflow of steam therebetween into and from said chamber whereby said valvemember is prevented from responding to variations in the back pressureof a magnitude less than said predetermined magnitude both at backpressures above and below a pressure of the aforesaid predeterminedmagnitude, and auxiliary valve means operable to be opened upon apredetermined increase in the back pressure above a back pressure ofsaid predetermined magnitude.

20. In a device for use with a steam locomotive wherein steam exhaustedfrom means in the locomotive in which the steam is expanded to performwork builds up a back pressure and in which such steam is utilized toinduce a draft through the fire box of the locomotive of a magnitudeproportionate to the magnitude of the back pressure, outlet meansthrough which the exhausted steam may also be discharged to theatmosphere, valve means in said outlet means for controlling flow ofsteam to the atmosphere through said outlet means, said valve meansincluding at least one portion responsive to the back pressure andoperable to be opened upon increase of the back pressure beyond a,predetermined magnitude to permit discharge of sufiicient steam to theatmosphere through said outlet means to prevent a substantial increasein the back pressure beyond said predetermined magnitude, the pressureresponsive portion being constructed and arranged to embody a chamber towhich steam may be admitted slowly and from which steam may escapeslowly whereby said portion is prevented from responding to variationsin the back pressure of a magnitude less than a pressure of saidpredetermined magnitude both at back pressures above and below apressure of the aforesaid predetermined magnitude, and auxiliary valvemeans operable to be opened upon a predetermined increase in the backpressure above a back pressure of said predetermined magnitude.

21. In a device for use with a steam locomotive wherein steam exhaustedfrom means in the locomotive in which the steam is expanded to performwork builds up a back pressure and in which such steam is utilized toinduce a draft through the fire box of the locomotive of a magnitudeproportionate to the magnitude of the back pressure, outlet meansthrough which the exhausted steam may also be discharged to theatmosphere, valve means in said outlet means for controlling flow ofsteam to the atmosphere through said outlet means, said valve meansincluding a plurality of pressure responsive valve members operable tobe opened upon increase of the back pressure beyond a predeterminedmagnitude to permit discharge of suflicient steam to the atmospherethrough said outlet means to prevent a substantial increase in the backpressure beyond said predetermined magnitude, each I of said pressureresponsive valve members including a fixed member and a movable membershaped to define a chamber therebetween and sized to aiford restrictedflow of steam therebetween into and from said chamber whereby said valvemember is prevented from responding to variations in the back pressureof a magnitude less than said predetermined magnitude both at backpressures above and below a pressure of the aforesaid predeterminedmagnitude, and auxiliary valve means operable to be opened upon apredetermined increase in the back pressure above a back pressure ofsaid predetermined magnitude, said auxiliary valve means also includinga fixed member and a movable member formed to provide a chambertherebetween and to afiord restricted flow of steam into said chamber tothereby render the auxiliary valve means responsive to the aforesaidincrease in pressure and to prevent response of the auxilary valve meansto variations in the back pressure of a magnitude less than theaforesaid predetermined magnitude at pressures above the pressure atwhich the auxiliary valve means are opened.

22. In a device for use with a steam locomotive wherein steam exhaustedfrom means in the locomotive in which the steam is expanded to performwork builds up a back pressure and in which such steam is utilized toinduce a draft through the fire box of the locomotive of a magnitudeproportionate to the magnitude of the back pressure, outlet meansthrough which the exhausted steam may also be discharged to theatmosphere, valve means in said outlet means for controlling fiow ofsteam to the atmosphere through said outlet means, said valve meansincluding at least one portion responsive to the back pressure andoperable to be opened upon increase of the back pressure beyond apredetermined magnitude to permit discharge of suflicient steam to theatmosphere through said outlet means to prevent a substantial increasein the back pressure beyond said predetermined magnitude, the pressureresponsive portion being constructed and arranged to embody a chamber towhich steam may be admitted slowly and from which steam may escapeslowly whereby said portion is prevented from responding to variationsin the back pressure of a magnitude less than a pressure of saidpredetermined magnitude both at back pressures above and below apressure of the aforesaid predetermined magnitude, control means forpreventing operation of said valve means until the back pressureincreases in a predetermined magnitude above the aforesaid predeterminedmagnitude, and auxiliary valve means operable independently of thecontrol means and adapted to be opened upon an increase in the backpressure over and above the aforesaid predetermined magnitude to permitdischarge of additional steam through the outlet means to theatmosphere.

BERT C. BERTRAM-

